Born in Chicago on December 28, 1936, Jim McDermott earned a bachelor's degree from Wheaton College in 1958 and an MD from the Abraham Lincoln School of Medicine at the University of Illinois in 1963. After pursuing his specialty in psychiatry at the University of Washington Medical Center, McDermott served with the U.S. Navy Medical Corps in New York from 1968-70. He then returned to Seattle where he practiced medicine on a part-time basis while serving as a member of the State House of Representatives (1971-72) and then as a State Senator (1975-87).

McDermott, a Democrat, left the state legislature in 1987 and served briefly as a medical officer with the U.S. Foreign Service in tropical Africa. The following year, he returned to Washington State to run for an open Seventh Congressional District seat and won in a landslide. McDermott was thereafter re-elected every two years until 2016, when he announced that he would be leaving Congress when his term ended in January 2017. During his years in the House of Representatives, McDermott was also a longtime member of the Congressional Progressive Caucus. The Political Action Committee of the Democratic Socialists of America (DSA) was among his most noteworthy supporters.

On January 8, 1997, while sitting as ranking minority member of the House Ethics Committee which was then hearing charges against Republican House Speaker Newt Gingrich, McDermott received (from a Florida couple) a tape of an illegally recorded cell-phone conversation that recently had taken place between Gingrich and some fellow Republican congressional leaders, including John Boehner. McDermott then violated federal law by giving access to this stolen conversation to the New York Times, which quoted excerpts in a story on January 10. McDermott resigned from the Ethics Committee three days later, after the Florida couple identified him as the recipient of their tape. When Boehner subsequently sued McDermott, the court determined that the latter had engaged in “willful and knowing misconduct” that “rises to the level of malice,” and ordered the congressman to pay Boehner’s legal costs (over $600,000) plus $60,000 in damages.

In September 2002 McDermott and fellow Democratic congressmen David Bonior and Mike Thompson traveled to Baghdad, where they embraced Iraqi dictator Saddam Hussein and created propaganda in his behalf, publicly expressing doubt about the George W. Bush administration’s claims that Saddam's regime had manufactured and stockpiled weapons of mass destruction (WMD). Interviewed upon his return to the United States, McDermott told ABC's George Stephanopoulos that Bush was “trying to provoke a war” and would undoubtedly “lie to the American people in order to get us into this war.” By contrast, McDermott said of Iraq's claim that it possessed no WMD: “I think you have to take the Iraqis ... at their face value.” He also denounced the United Nations' “coercive” weapons-inspection program and emphasized that “Iraq did not drive the inspectors out, [but the U.S.] took them out. So they should be given a chance.”

The financing of the three congressmen's trip to Iraq merits some discussion at this point. Bert Sacks, an activist with the Interfaith Network of Concern for the People of Iraq, initially told McDermott that his organization would help pay for the trip. Shortly before the lawmakers were scheduled to depart for Badgdad, however, Sacks unexpectedly received a phone call from a man named Muthanna Al-Hanooti, who headed a Michigan-based Muslim nonprofit group called Life for Relief and Development (LRD), which regularly shipped food and medicine to Iraq. Al-Hanooti was also a DC lobbyist for the Iraqi Islamic Party, and an official of both CAIR-Michigan and Focus on American and Arab Interests and Relations. He described himself to Sacks as "a concerned Iraqi-American citizen" who wanted to bankroll the congressmen's trip. Sacks gladly accepted Al-Hanooti's offer.

It was later learned, however, that Al-Hanooti was acting as a paid operative of Saddam's intelligence agency, which gave the LRD leader $34,000 with which to fund the lawmakers' trip in its entirety. Al-Hanooti's task in this scheme was to use unwitting and credulous American politicians—in this case McDermott, Bonior and Thompson—as propaganda tools to undermine the UN sanctions against Iraq. Specifically, he took them on tours where they could see firsthand the suffering that the sanctions were allegedly inflicting on Iraqi children—confident that the lawmakers would subsequently denounce the sanctions and the Bush administration to the American people. In exchange for his efforts, Al-Hanooti received vouchers for 2 million barrels of Iraqi oil from Saddam's government.

Also accompanying the congressmen on the trip was the Detroit-area, Iraqi-American businessman Shakir al-Khafaji, who gave McDermott a $5,000 check that was promptly deposited into a special fund which the Washington Democrat had set up to cover legal fees related to his involvement in the aforementioned cell-phone scandal.

A longtime advocate of single-payer socialized medicine, McDermott in June 1996 joined Quentin Young and others in addressing a major healthcare-reform conference in Seattle. The congressman told his audience that it was vital to “get the profiteers out of health care. Period!”

Seven years later, McDermott and 20 fellow congressmen (including John Conyers and Dennis Kucinich) introduced HR-676, a bill designed to establish a government-run, “Medicare-for-all” system. McDermott again introduced similar bills in 2009 and 2011. In 2011 he said that while “the new health care law [Obamacare] made big progress towards covering many more people and finding ways to lower cost,” “the best way to reduce costs and guarantee coverage for all is through a single-payer system like Medicare.”

In the summer of 2007, McDermott traveled to Havana, Cuba for a “fact-finding trip” whose costs were covered by the Center for Democracy in the Americas. Six years later, he joined 58 fellow House Members in urging President Barack Obama to end the restrictions limiting American travel to Cuba.

On December 22, 2009, McDermott was one of 33 U.S. Representatives who signed a letter to Hillary Clinton which (a) called on the Secretary of State to pressure the Israeli government end its ban on Palestinian student travel from Gaza to the West Bank, and (b) “applaud[ed]” Mrs. Clinton's “initiative to increase U.S. funding for Palestinian universities and educational programs in Gaza and the West Bank.”

On January 27, 2010, McDermott was one of 54 Members of Congress who signed a letter calling on President Obama to use diplomatic pressure to end Israel's blockade of Gaza—a blockade that had been imposed in order to prevent the importation of weaponry from Iran and Syria.